Why is El Nino bad news for Western Rock Lobster?

By

David Griffin, John Wilkin, Alan Pearce (CSIRO, NIWA)Chris Chubb and Nick Caputi (Fisheries WA)

Thankyou FRDC, Kim Badcock, Jeff Dunn, Russ Fiedler, Jim Mansbridge, Thomas Moore, Chris Rathbone, Ken Ridgway, Andreas Schiller, Paul Tildesley, Jason Waring, Neil White,And many external agencies for various data.

This talk

• Satellite-based currents and advection of lobster larvae

• Hydrodynamic modelling progress report

• Future directions

Three satellite views of the Leeuwin Current

Diurnal vertical migration of modelLarvae and velocity summation in layers

Conclusions (part 1)

• A consequence of vertical migration is that larvae can hold station off WA

• During El Nino, the wind effect predominates and more larvae are lost to the north.

• During La Nina, the Leeuwin current wins and more larvae are lost to the GAB.

• So, something else must be happening, eg variable mortality or growth, to explain why observed settlement variability is so much less in El Nino

Conclusions (part 2)

• ACOM3 provides dynamically consistent OBCs for regional models, but needs further development

• ROMS makes beautiful eddies,streamers, etc, but spurious flows remain. Assimilating SBTs works; we’re now working on SBSs (synthetic bathysalinographs).

Future directions

• SRFME/FRDC/NASA/ONR funding sought for

• Data assimilation in ACOM3

• Data assimilation in ROMS

• Bio-geochemical cruises, imagery and models

• Lobster larvae diet, growth and condition

Thankyou